Syntheses of procyanidin B2 and B3 gallate derivatives using equimolar condensation mediated by Yb(OTf)3 and their antitumor activities

Synthesis of procyanidin B2 and B3 gallate derivatives, 3-O-gallate, 3″-O-gallate, and 3,3″-di-O-gallate, were synthesized using equimolar condensation mediated by Yb(OTf)3. Synthesized compounds showed significant antitumor effects against human prostate PC-3 cell lines. Their activities were weaker than well-known EGCG and prodelphinidin B3.